How to Grow Hydroponic Lettuce

Growing lettuce in your hydroponic farm doesn’t have to be complicated. Get growing today, and harvest your own fresh greens sooner than you can believe. Our how-to guide will guide you through the essential steps to growing your own hydroponic lettuce, one of the best vegetables to grow hydroponically.

hydroponic lettuce

How to Grow Hydroponic Lettuce: Step by Step

Choose your lettuce variety and purchase your seeds.

There are several types of lettuce you can substitute, so make sure you choose the variety that fits your needs. Consider taste, mature plant size, and nutrition information (check out our review of the best hydroponic nutrients!). You can even try more than one type of lettuce if you prefer. Once you’ve chosen your lettuce, find a quality seed provider and purchase enough seed to meet your harvest quota plus extra to accommodate the fact that not every seed will likely sprout.

Germinate your seeds.

During this process, many people like to use seed plugs that sit directly in a hydroponics system that is already set up. Put a few seeds in each plug and place them under fluorescent or natural light. Germinating seeds will only take a few days and requires the seeds to have light, ample water, and nutritional supplements that help promote strong root growth. Your seeds have germinated once you see a sprout coming out of your seed plug.

Germinating lettuce likes artificial light to be just a couple inches from the growing beds, mid-seventies in temperature, and long light schedules (12 to 14 hours of light each day). For artificial light, we suggest an LED grow light.

Transplant to primary hydroponic setup.

Choose your strongest seedlings from each plug for transplanting. Check for any pests, fungus, or disease to ensure that your crop yields a good harvest and doesn’t spread anything to your strong seedlings. Remove your seedlings from the seed plug and move the seedlings into the individual growing cups for whatever hydroponic system you are using.

Before transplanting, be sure to test the water chemistry of your setup to ensure that nutrient levels and pH are optimal for plant growth. Lettuce needs a water pH that is stable between 5.5 and 6.0. The pH is important for the plants, because it is one of the main determinants of whether a plant can absorb nutrients. We’ve written a super helpful article identifying the best pH meters for hydroponics, for a variety of budgets.

Depending on the pH levels, the lettuce either won’t be able to absorb enough fertilizer and won’t grow quickly or not at all, or the lettuce will absorb too much of the fertilizer and cause damage to the foliage. Check nitrogen, calcium, phosphorus, and other nutrient levels to make sure that they are within an acceptable range for your seedlings.

Seedlings also like temperatures in the mid-seventies and long hours of light each day.

Keep your setup stable and watch your lettuce grow.

Fertilize and test the water chemistry of your setup often. Your exact schedule for feeding the lettuce will depend on the products you choose. Be sure to fix any chemical abnormalities as soon as they surface to prevent damage to your plants. The last thing you want is leaf burn on your lettuce!

Harvest your crop and enjoy.

You can begin harvesting lettuce leaves before you have mature full heads on your plants. Lettuce grows quickly, so it will only take a few weeks before you have harvestable leaves, and just a couple weeks more than that before you have full heads.

how to grow hydroponic lettuce

Hydroponic Lettuce Systems

Hydroponic lettuce, much like other leafy greens, grows very well in all types of vertical systems. The plants don’t take up much space, so you can easily produce a lot of crop in very little floor space.

Deep water culture, including the Kratky method, is another good choice for a garden primarily growing lettuce, and it is also the most common. This method, with a floating platform on large water bins, is favored because the substantial volume of water makes it harder for water chemistry to change if you accidentally make a mistake while supplementing. You can avoid the investment into the pumping equipment necessary with most deep water culture methods by using the Kratky method, which utilizes passive water flow rather than pumped.

Nutrient film technique is an option that requires smaller plant beds than deep water culture, but you do have to be more careful with how you supplement using this technique than with deep water culture, because the volume of water is smaller in this method and easier to create unwanted fluctuation.

Ebb and flow systems flood the growing beds with water and nutrient solutions and then drain the beds back out again. This is different from the other systems discussed, because the plants are not constantly inundated by water.

Which system is best for your hydroponic lettuce farm will depend on where you’re looking to build, the amount of available space, and your experience level.

Hydroponic Lettuce Nutrients

Hydroponic lettuce will need nitrogen, calcium, phosphorus, potassium, magnesium, sulfur, iron, manganese, copper, zinc, and chlorine to thrive. Whether you actually have to supplement these nutrients and how much will depend on the chemistry of the water you’re using. Test your water before you begin supplementing to determine how much of each you need or if you need to remove some of the chemicals before you begin.

Chlorine can be a particular issue for growers, but there are commercial products available to remove excess chlorine if this proves to be something you need.

Seedlings may grow better on the higher end of the pH range, whereas mature lettuce often do better if the pH is lowered closer to the bottom end of the preferred range.

If you’re choosing to try multiple varieties of lettuce, it is recommended to research the individual varieties’ nutritional needs to make sure that your prospective varieties require the same or very similar conditions to thrive. This will ensure that you are receiving the maximum yield from your garden and you don’t accidentally set yourself up for crop failure.

How to Store Hydroponic Lettuce

Since hydroponic lettuce is grown without pesticides or herbicides, you don’t need to worry about washing hydroponic farm lettuce. You also eliminate the risk of E. Coli infection by eating hydroponically grown lettuce, since it isn’t grown in fertilizer that comes from animal waste.

Keeping hydroponic lettuce fresh after harvest is simple but slightly different from the way traditionally farmed lettuce is stored. When harvesting hydroponic lettuce, pull the entire plant up and keep the root system intact. You can trim the roots so they are less cumbersome, but keeping the roots on the lettuce allows the plant to keep absorbing water and keep its leaves crisp.

Greens are best stored in the refrigerator’s vegetable crisper drawer in a damp, breathable cloth. Only remove leaves from your lettuce head as you are about to use them.

We hope you found our guide helpful for growing hydroponic lettuce. Growing hydroponic plants is one of the most rewarding benefits to having a hydroponic system. Don’t forget to check out our other article where we focus on how to grow hydroponic tomatoes.

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